1. Field of the Invention
The present general inventive concept relates to an inkjet image forming apparatus, and more particularly, to an inkjet image forming apparatus including an inkjet head having a nozzle portion, a length of which in a main scanning direction corresponds to a width of a printing medium, and a cap member to cap the nozzle portion.
2. Description of the Related Art
In general, an inkjet image forming apparatus forms images by ejecting ink from an inkjet head, which reciprocates in a main scanning direction (shuttle type inkjet head), onto a sheet of paper conveyed in a sub-scanning direction. The inkjet head includes a nozzle portion including a plurality of nozzles through which ink is ejected. Ink droplets that are not ejected remain around the nozzle portion. When the nozzle portion is exposed to air when a printing operation is not performed, the ink droplets around the nozzle portion may harden, and impurities, such as fine dust in the air, may attach to the nozzle portion. The hardened ink or impurities may change an ink ejecting direction, thereby degrading printing quality. In addition, since a humidity of the ink in the nozzles evaporates, the nozzles portion may become clogged with ink.
Recently, high speed printing has been performed using an inkjet head (array inkjet head) including a nozzle portion having a length in a main scanning direction corresponding to a width of a sheet of paper. In the inkjet image forming apparatus, the inkjet head is fixed, and sheets of paper are conveyed in a sub-scanning direction. Therefore, a driving unit for the inkjet image forming apparatus has a simple structure, and a printing operation can be performed at a high speed. In the inkjet image forming apparatus, the length of the nozzle portion corresponding to A4 paper is about 210 mm, without considering a printing margin in a width direction of the paper. Since the array inkjet head ejects ink in a fixed position unlike the shuttle type inkjet head reciprocating in the main scanning direction, it is difficult to fix operational problems when some of the nozzles are clogged or when an ejecting direction of the ink is changed due to impurities.
Therefore, when the printing operation is not performed, the nozzle portion should be isolated from the outside (e.g., an environment surrounding the nozzle portion).